1. Field of the Invention
The present invention relates to a disk array apparatus, and, more particularly, to a maintenance technique for use when a disk array unit in the disk array apparatus is replaced.
2. Description of the Related Art
A disk array apparatus has a plurality of disk array units. Each of the disk array units stores firmware for achieving the function of the disk array unit, and executes the stored firmware, whereby the disk array apparatus operates. If a failure occurs in one of the disk array units in the disk array apparatus, the entire disk array unit is required to be replaced.
A disk array apparatus has a plurality of redundant disk array units for achieving the same function, because it is required to maintain uninterrupted operation. In addition, the disk array apparatus is required to prevent degradation of its performance after a faulty disk array unit included therein is replaced. If one of the disk array units malfunctions, that is, does not fulfill its function, this causes degradation of performance of the disk array apparatus. In order to prevent the degradation, a replacement disk array unit is required to operate by executing its firmware whose version number is the same as that of disk array units that are operating in the disk array apparatus.
As a known method used when a replacement disk array unit is disposed in a disk array apparatus, there is a firmware download method of making the version number of firmware stored in the replacement disk array unit conform to that of firmware stored in disk array units that are operating in the disk array apparatus. For example, a first disk array unit storing firmware and disposed in the disk array apparatus is replaced with a second disk array unit in the following manner. First, the version number of firmware stored in the second disk array unit is compared with that of firmware stored in a third disk array unit that is operating in the disk array apparatus. If the version numbers of a plurality of pieces of firmware stored in the second and third disk array units are not the same, the firmware stored in the third disk array unit is downloaded into a firmware storage area in the second disk array unit. The second disk array unit performs a predetermined operation by executing the firmware downloaded into its firmware storage area (see, for example, Japanese Unexamined Patent Application Publication No. 2005-71042).
If a malfunction occurs while a disk array apparatus is operating, it is required to recreate a situation in which the malfunction occurred in the disk array apparatus so as to investigate the cause of the malfunction. However, firmware that is not executed by a disk array unit is not taken into consideration in a known technique. Accordingly, a situation in which a malfunction occurred cannot be accurately recreated.
In addition, if a disk array apparatus having disk array units each capable of storing a plurality of pieces of firmware in its firmware storage area is restarted, each of the disk array units may execute firmware different from firmware which it executed before the disk array apparatus was restarted.
In order to overcome the above-described difficulties, it is an object of the present invention to make the version numbers of a plurality of pieces of firmware stored in functional disk array units in a disk array apparatus conform tot each other and make the version numbers of a plurality of pieces of firmware executed by the functional disk array units in the disk array apparatus conform to each other.